/Engine/Plugins/Runtime/GameplayAbilities/Source/GameplayAbilities/Public/GameplayEffect.h
Attempts to calculate the contribution of the specified GE to the captured attribute given the specified parameters. Can fail if the spec doesn't have a valid capture yet.
True if the bonus magnitude was successfully calculated, false if it was not
bool AttemptCalculateAttributeContributionMagnitude ( const [FAggregatorEvaluateParameters](API\Plugins\GameplayAbilities\FAggregatorEvaluateParameters) & InEvalParams, [FActiveGameplayEffectHandle](API\Plugins\GameplayAbilities\FActiveGameplayEffectHandle) ActiveHandle, float & OutBonusMagnitude ) const